如何糾正分割錯誤？

Question

程序下面顯示錯誤：“ segmentation fault（core dumped）”。

它應該使用vector顯示平面文件記錄，讀取記錄的每一行並獲取該字段的記錄，然后推回到vector r_record。 然后推回桌子。

//.. includes
#define LIMIT 72
#define FIELD 25

using namespace std;
typedef vector <string> record_t;
typedef vector <record_t> table_t;
char line[FIELD];   
string s_field;
table_t table;
record_t r_record;

void getField(char s[LIMIT])
{
    char field[LIMIT];      
    int i=0;
    r_record.clear();
    while(s[i]  != '\n')
    {   
        if (s[i] != '\t' )
        {                                                       
            field[i] = s[i];
            //*s_field = *s_field+1;        
        }               
        i++;
    }
    s_field = field;            
    r_record.push_back(s_field);
} 

void getLine(FILE *fp)
{
    char c;
    int j=0;    
    table.clear();
    l1:while ( (c = getc(fp)) != EOF ) 
    {  
        if( c != '\n' )
        {
           line[j] = c;

        }
        j++;
    }   
    getField(line);
    table.push_back(r_record);
    if(c != EOF)
        goto l1;                        
    cout<<table.size(); 
} 

int main()
{
    double total_time;  
    clock_t start, end;
    start = clock();//time count starts 
    FILE *f1;   
    f1 = fopen("somesamplefile.txt","r+");      
    getLine(f1); 

    end = clock();//time count stops 
    total_time = ((double) (end - start)) / CLOCKS_PER_SEC; //calulate total time
    printf("\nTime taken to print  %f\n", total_time);

    return 0;
}

Answer 1

我將關注@MattMcNabb所發表的有關在將值分配給字符串中的各個字符之前檢查限制的評論。

此外，您還沒有在getField中將終止field getField null。 沒有那個，聲明

    s_field = field;

可能會超出范圍訪問數據並導致未定義的行為。

void getField(char s[LIMIT])
{
    // **** CORRECTION *****
    // I am guessing you meant to use field[FIELD].
    // char field[LIMIT];      
    char field[FIELD];

    int i=0;
    r_record.clear();

    // **** CORRECTION *****
    // Add a check to stop going beyond the limits of the array.
    // while(s[i]  != '\n')
    while( i < FIELD-1 && s[i]  != '\n')
    {   
        if (s[i] != '\t' )
        {                                                       
            field[i] = s[i];
            //*s_field = *s_field+1;        
        }               
        i++;
    }

    // **** CORRECTION *****
    // Add this
    field[i] = '\0';

    s_field = field;            
    r_record.push_back(s_field);
} 

另外，我想你打算用

char line[LIMIT];   

代替

char line[FIELD];   

Answer 2

衷心001 25 city1衷心002 26 city1衷心003 27 city1衷心004 25 city1衷心005 28 city1衷心006 29 city1衷心007 30 city1衷心001 25 city1衷心002 26 city1衷心003 27 city1

在文本中具有制表符分隔格式，應顯示不正確

校正后的程序

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <string>
#include <cctype>
#include <cstdio>
#include <ctime>
#include <vector>
#include <sstream>
#include <algorithm>
#include <iterator>
#include <sys/stat.h>
#include <iterator>
#include <exception>
#include <dirent.h>
#include <unistd.h>
#include <map>
#include <unordered_map>
#include <sys/timeb.h>
#include <stdexcept>                                                     // std::out_of_range
#include <time.h>
#define LIMIT 22
#define FIELD 8

using namespace std;
typedef vector <string> record_t;
typedef vector <record_t> table_t;
char line[LIMIT];   
string s_field;
table_t table;
record_t r_record;

vector <string>::iterator t_record;

void getField(char s[LIMIT])
{
    // **** CORRECTION *****
    // I am guessing you meant to use field[FIELD].
    // char field[LIMIT];      
    char field[FIELD];

    int i=0;
    r_record.clear();

    // **** CORRECTION *****
    // Add a check to stop going beyond the limits of the array.
    // while(s[i]  != '\n')
    while( i < FIELD-1 && s[i]  != '\n')
    {   
        if (s[i] != '\t' )
        {                                                       
            field[i] = s[i];
            //*s_field = *s_field+1;        
        }               
        i++;
    }

    // **** CORRECTION *****
    // Add this
    field[i] = '\0';

    s_field = field;            
    r_record.push_back(s_field);    
} 

void getLine(FILE *fp)
{
    char c;
    int j=0;    
    table.clear();
    l1:while ( j < LIMIT-1 ) 
    {  
        c = getc(fp);
        if( c != '\n' )
        {
           line[j] = c;
            j++;
        }                 
    }   
    line[j] = '\0';
    if( c!= EOF )    
    {       
        getField(line);
        table.push_back(r_record);
        j=0;
        goto l1;
    }

} 

int main()
{
    double total_time;  
    clock_t start, end;
    start = clock();//time count starts 
    FILE *f1;   
    f1 = fopen("somesamplefile.txt","r+");      
    getLine(f1); 
    for(t_record = r_record.begin(); t_record != r_record.end(); ++t_record )
    {
      cout <<*t_record <<endl;
    }
    cout<<table.size(); 
    end = clock();//time count stops 
    total_time = ((double) (end - start)) / CLOCKS_PER_SEC; //calulate total time
    printf("\nTime taken to print  %f\n", total_time);

    return 0;
}